Just thought I'd write out something somewhat comprehensive on Vergil's abilities. WELCOME TO TL;DR LAND, KIDDIES.
Starting out with the basics: He's a half-demon son of Sparda, so Vergil is going to have haxx speed and strength compared to normal humans. However, he tends to rely on the former more than the latter, given his style of fighting seen within the game. His main mode of attack is through using his sword Yamato, usually coupling his skill with the blade along with crazy inhuman amounts of speed to run circles around his enemies. He has high levels of endurance and can therefore take quite the beating and still have enough energy left to fight. Also, objects that would hurt normal humans most likely won't injure him (although this, of course, probably just depends on the object itself and the extremity of the, er, situation). Bullets, for instance, if they even manage to hit him in the first place, will barely put a scratch on him. The force of impact would still hurt or sting a little, but it wouldn't result in bad end. |D From the injuries that he does sustain, he'd be able to heal from them faster than a normal human would.
Now onto the specifics.
YAMATO
Yamato is Vergil's main weapon and a memento of his father, Sparda. It's actually an O-katana, or basically a longer than average katana. Because of its extended length, this type of weapon makes it difficult for the individual to engage in very close combat, simply because there has to be a good amount of space in between the two combatants to even consider wielding it. Therefore, Vergil fights using the hilt of Yamato as much as he does with the actual blade, especially if he finds himself within close quarters since that does not require nearly as much space.
Example: Vergil's basic combo with Yamato in DMC3 is the... Yamato Combo (△, △, △). The first two hits is Vergil basically making two quick strikes with the hilt of the sword, in turn giving him enough space to open up with a very large and fast horizontal slash of the blade, knocking his enemies back. (Or preferably slicing them in two. Whatever works.)
At medium range is where Yamato works best, giving Vergil enough room to execute the long, sweeping attacks. This is also his most comfortable range, because once he has you at this distance, it's all a matter of making sure you don't find an opening to get in close or that you don't run off anywhere; usually an easy task, considering Vergil's speed. All the fancy footwork and swordplay goes here.
At long range, Yamato only has one attack at its disposal, Judgment Cut, but it's probably one of Vergil's most dangerous techniques. To copy pasta from
this very useful FAQ, Judgment Cut "starts off with Vergil dashing back, then taking his draw stance. He then slashes and quickly withdraws the Yamato back to the scabbard, whilst creating a warping cone. Within the cone, 'sphere-slashes' appear, that inflicts tremendous knock back to anything it hits." And since this attack probably breaks over nine thousand laws of physics, it can be assumed that Vergil's demon power is what helps aid in creating these "spheres". He can create several consecutively at a rapid pace, even making the line of attack follow the one he's trying to hit. Consider them one big ball of force, with many "slashes" and "cuts" from Yamato contained within them. Though the quote from the FAQ states that it'll create a huge knockback to anything it hits, keep in mind that Vergil fights only demon foes in the game; if Judgment Cut is ever used against a regular human opponent, it will end in a bloody mess. Most especially if they are caught inside the attack, and not just in the close vicinity.
The one drawback of this attack is the time it takes to execute it. Vergil has to take the time to focus, so any interruptions will most likely cancel this move. >: B'aww.
SUMMONED SWORDS
(Vergil using Summoned Swords and also Judgment Cut, fuck yeah.)
Vergil despises guns, so instead he uses his Summoned Swords attack as a form of his projectile weapons. I personally think that these are the coolest things ever. |D As the name suggests, Vergil summons up blue, glowing swords out of thin air and sends them flying at the enemy. Though mainly used as a weapon, they can also function as a type of shield if the occasion calls for it.
Despite being "summoned", which suggests some sort of magical property, the swords are very much material and solid objects. If they hit something with enough force (and they usually do, since Vergil is the one sending them flying), they shatter on impact, as if made of glass. Very sharp, pointy, and painful glass. Again, though, Vergil is usually only sending them to demonic-like creatures in the game; anything less and there's a high probability the summoned sword might run itself right through them. D:
As mentioned before, Vergil can use this technique defensively as well. Since they are solid objects, he can use them to block incoming swords/bullets/etc. by having them protectively surround him. And yet again, if hit with enough force, these swords will shatter, so it's by no means a perfect shield. The good thing, however, is that he can summon these at a rapid pace (both defensively and offensively), even if he is busy executing another attack. (As you can see from the image above.)
EVASIVE MANEUVERS DO A BARREL ROLL
Vergil is fast. I mean, really fast. As I mentioned before, it is probably one of the most prominent, if not the most prominent feature of his fighting abilities. In all aspects of combat, he relies on his speed to defeat his enemies, but it's even more important when it comes to avoiding them.
In the game, Vergil's Darkslayer style is very similar to Dante's Trickster style. What does that mean? Basically a lot of uber-quick teleporting abilities. I'm inclined to believe that it isn't actual teleportation per se, just Vergil moving faster than the eye can register from point A to point B. The move is almost instantaneous, which gives him both the advantage of surprise and also the fact that he's... right there in front of you. ready to slice you in two. But for the sake of getting away from the enemy, he can basically apply this technique in any direction. (Even above and, if the surrounding area allows it, below the enemy.)
This technique, however, has limited range. He's not going to be able to suddenly appear 2 miles away from you or anything to that extremity. It does allow him to at least put him in medium-range, AKA the best place for him to follow up with Yamato.
When it concerns general speed and not necessarily techniques, what I mentioned in the first paragraph applies. Very inhumanly fast, etc. etc. Regular humans will have a very difficult time catching up with him.